Condenser.



WITNESSES H Y .lHVE/l'ifOR-f I f v Elihu Thomson, MA/M UNITED STATESPATENT OFFICE.

ELIHU THOMSON, OF SWAMPSGOTT, MASSACHUSETTS, ASSIGNOR TO GENERALELECTRIC COMPANY, A CORPORATION OF NEW YORK.

com'mnsnn.

Specification of Letters Patent.

Patented Oct. 20, 1908.

Application filed. Kay 5, 1904. Serial No. 206,479.

To all whom it mayconcem:

Be it known that I, ELIHU THoMsoN, a. citizen of the United States,residing at Swampscott, in the county of Essex and State ofMassachusetts, have invented certain new and useful Improvements inGondensers, of which the following is a speci tication.

In working with high voltage condensers in which adjacent metalconducting plates of opposite polarity are separated by acomparativelythick layer of dielectric, there is a concentration of thedielectric stress upon the edges of the conducting plates, while be-'tween the plates the stress is nearly uniform through the layer ofdielectric. By reason of this difference in the stress due to thecharge, the tendency to break down the insulation between the edges ofthe conducting plates is much greater than between the bodies of theplates. This excess of stress on the edges of a conducting plate is notso marked where the voltage between adjacent working platesis not sogreat and the layer of dielectric material is thinner.

I have found that the liability of break down in high voltage condensersmay be greatly diminished by placing a number of intermediate conductingplates between the main or active plates of a condenser. Each of theintermediate plates is separated from adjacent conducting strips orplates by thin layers of dielectric. The intermediate plates are notelectrically connected to each other or to either of the main plates. Inarranging the conducting plates in high voltage condensers I prefer todisplace adjacent main conducting plates with respect to each other sothat the distance between corresponding edges is considerably greaterthan the distance between the bodies of the plates. The intermediateunconnected conducting plates may be arranged so that their edgesterminate in the sloping planes connecting the corresponding edges ofadjacent main plates. 1

By the construction described thestrains between adjacent main platesare equalized in a way which would not be the case if the intermediateunconnected plates were not employed. These intermediate platesdistribute the stress over separate dielectric layers between them andprevent the existence of extended weak areas between the main plates,suchas might otherwise-exist.-

Moreover as the distance between the edges of the main conducting platesis considerably greater than the distance between the bodies of theplates, the inequality in distribution of the charge upon the plates isless objectionable than would otherwise be the case.

The various features of novelty which characterize my invention arepointed out with particularity in the claims annexed to ipnd forming apart of this specification. or a better understanding of my invention,however, reference may be had to the accompanying drawings anddescription in which I have illustrated and described one embodiment ofmy invention. 4

Of the drawings, Figure 1 is a perspective view showing the arrangementof conducting plates in the condenser; Fig. 2 is a sectional sideelevation; and Fig. 3 is a view taken at right angles to Fig. 2 on alarge scale showing the arrangement of the plates in a portion of thecondenser. I

Referring to the drawings, five similar and parallel plates or sheets Aof conducting material such as tinfoil are shown as connected togetherat one end by a conducting strip or sheet B which may also be made oftinfoil. Between each adjacent pair of these plates is located a similarplate C. The plates C are connected by a strip or sheet D. The plates Aare displaced laterally with respect to C. Between adjacent plates A andC are located a number of intermediate metal plates or conductors E.These are shown best in Figs. 2 and 3 and may alsolbe in the form ofsheets of tinfoil. At each side of each of the intermediate plates E isplaced a suitable layer of dielectric.- This may consist of a number ofsheets of paraftined paper F. p

In the construction'shown plates A and C are prolonged in undiminishedwidths to the connecting sheets B and D. The portion of the top'plate Ato the left of the line 1 1 in Fig. 1 may, however, be regarded as theterminal portion of the plate or conductor, and the portion of the plateto the right of the line 1 1 may be regarded as the body or workingportion of the plate. Each ofthe plates A and C shown may similarly beregarded as composed of a terminal portion and a body or workingportion. The terminal portion of the plate may well, in many cases, bemade of a width much less than that of the body of the plate or mayindeed be inthe form of a wire or rod or the like.

In the construction illustrated the body portions of each pair ofadjacent plates A and 0 form the parallel sides of a parallelepiped,none of the plane angles of which are right angles. The edges of theintermediate equalizing conductors all terminate in the planes formingthe side walls of this parallelepiped. The surfaces in which theyterminate are, however, not necessarily plane, but may be curved to aconsiderable degree, provided they approximate in arrangement thatdescribed above The paper sheets may extend as usual beyond the edges ofthe metal sheets. The assembled condenser plates and separating layersof paper are thus embodied in a block G of paraflin or the like as shownin Fig. 2. The plates A and C form the active conductors of thecondenser, the plates A all being of one polarity and the plates C ofthe opposite polarity.

The stress-equalizing plates or conductors E are not electricallyconnected to each otheror to the active conductors. They serve, however,to equalize the forces tending to break down the dielectric betweenadjacent active conductors. This is due, I believe, to the fact thatthey prevent the existence of coincident weak spots under abnormalstress extending through any considerable thickness of what would,otherwise be a single dielectric layer between the main plates.

The form of my invention which I have illustrated and describedin'detail has given excellent results under severe conditions ofservice. 'I do not, however, intend that the claims hereinafter madeshall be limited to the particular construction described and.illustrated as it is obvious to those skilled in the art that changesmay be made in the form and arrangement of the condenser withoutdeparting invention.

What I claim as new and desire to secure by Letters Patentof the UnitedStates, is,

1. In a condenser, a pairof active conductors of opposite polarities,and one or more stress-equalizing conductors between iiid activeconductors and insulated therefrom the spirit of my 2. In a condenser, aset of active conduct ing sheets electrically connected together, asecond set of active conducting sheets also electrically connectedtogether, adjacent sheets of each set having interposed between them onesheet of the other set, and a number of conducting members locatedbetween each sheet of one set and the adjacent sheets of the other set,said conducting members being insulated from each other and from saidsheets.

3. In a condenser, a pair of parallel active conductors or sheets ofdifferent polarities, and one or more parallel stress-equalizingconductors or sheets located between said active conductors andinsulated therefrom.

4. In a condenser, a pair of parallel active plates of oppositepolarities displaced laterally with respect to each other, and anequalizing conductor between and parallel to said active conductors, theedges of said equalizing conductor terminating in the surface connectingcorresponding edges of the active conductors.

i 5. In a condenser, a pair of parallel and similar active conductors ofdiiierent polarities, one or more intermediate equalizing conductors,the edges of the working portions of the active conductors and of theequalizing conductors terminating in the plane forming the sides of aparallelepiped, none of the plane angles of which are right angles.

6. In a condenser, a pair of active conducting sheets or plates ofopposite polarities, and one or more insulated conductors locatedbetween them. 7. In a condenser, a pair of active conductors of oppositepolarities placed side by side, and an Insulated conductor placedbetween them.

8. In a condenser, a pair of conductors. in inductive relation with eachother. and arranged to be connected to a source of electricity so that adifference of potential exists between said plates, and an isolatedconductor interposed between and in inductive relation with each of thefirst mentioned conductors.

In witness whereof, I have hereunto set my hand this third day of May,1904.

ELIHU THOMSON.

Witnesses:

DUGALD McK. MGKILLOP, J OHN J. WALKER.

